The Universal Audio UAFX Ruby '63 Top Boost Amplifier is a model-specific virtual guitar amp pedal: an amp and speaker simulator that emulates a Vox AC30. Delicious Audio described it at launch as an "Authentic emulation of a Vox AC30, with three speaker options and three amp versions, stock and two common modifications, that capture the sparkling cleans and rich overdrive of the popular British amp"1. It arrived in July 2022, almost exactly a year after Universal Audio launched their UAFX pedals, as one of the first three UAFX amp pedals alongside the Woodrow '55 Instrument Amplifier and the Dream '65 Reverb-Amp2.
What it models and how it sounds
Sound On Sound's Dave Lockwood, reviewing the first three UAFX amp pedals in July 2022, explained that the Ruby '63 Top Boost Amplifier is actually two different Vox designs: a '61 pre-Top Boost model, and the Brilliant and Vibrato channels of a 1964 Top Boost example, both with a quartet of EL84s2. The pedal also carries a Vox vibrato/tremolo effect, which Lockwood traced to "something derived largely out of phase-shifter circuitry originally designed for use with electronic organs and accordions"2.
On how it feels to play, Lockwood's verdict was favorable:
"the Ruby Vox has glorious tube-rectifier 'bounce' that makes playing feel so much more like a real amp than a modeller"
Delicious Audio's later buying guide, by Griffin Jennings, called it "A fully-featured, stereo, authentic emulation of a Vox AC30"3. Premier Guitar, reviewing the related OX Stomp, grouped the Ruby with UAFX's own amp pedals as "UAFX's own amp pedals like the Ruby (Vox)"4.
Modes, footswitches and speaker options
The pedal runs in one of two modes, Live or Preset, and carries two footswitches2.
- Footswitches: two, reassignable via the UAFX Control app2
- Default assignment: Live and Preset mode, versus buffered Bypass2
- Modes: Live or Preset2
The modeled speaker options are 2x12 configurations of vintage 15W Celestion Silver Bulldogs, Alnico Blues, or modern G12Anniversary speakers. There are also bonus cabinet options: modern Alnico Blues, modern Matchless-style speakers, and modern Celestion Alnico Gold in a 1x12 cab2.
Connectivity, stereo and power
Audio connectivity consists of four unbalanced jacks, two in and two out2. There is a true stereo path through the unit if you use both inputs; feeding one input to both outputs runs two phase-locked instances, so a mono signal can still produce a stereo output2.
Power is external 9V DC through a standard 2.1mm center-negative pedal connector. Sound On Sound cautions that not all pedalboard power supply outputs may have the required 400mA current capacity, worth checking against your supply before slotting it into a board2.
The Ruby '63 runs on external 9V DC power only, using a standard 2.1mm center-negative pedal connector, so it cannot be powered from a battery2.
For players comparing amp-in-a-box and speaker simulation pedals, the Ruby '63 sits in a broader field that includes the Strymon Iridium, the Walrus Audio ACS1 MkII and the Joyo British Sound; see the Speaker Simulation Pedals page for the wider category.
Videos
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Questions
Does the Ruby '63 have MIDI?
No. As reviewed by Sound On Sound in July 2022, the pedal has no MIDI or external control, no effects loop and no headphone output. Universal Audio's later firmware 2.0 update added MIDI compatibility to some UAFX pedals, but the Ruby '63's own controls are limited to its two footswitches and the UAFX Control app.
What power supply does the Ruby '63 need?
It runs on external 9V DC power through a standard 2.1mm center-negative pedal connector. Sound On Sound notes that not all pedalboard power supply outputs may have the required 400mA current capacity, so a supply capable of delivering that much current is needed.
Does the Ruby '63 run in stereo?
Yes. It has two unbalanced inputs and two unbalanced outputs, and there is a true stereo path through the unit if you use both inputs. Feeding one input to both outputs runs two phase-locked instances, so a mono guitar signal can still produce a stereo output.
Which speakers can the Ruby '63 model?
The modelled speaker options are 2x12 configurations of vintage 15W Celestion Silver Bulldogs, Alnico Blues, or modern G12Anniversary speakers. There are also bonus cabinet options: modern Alnico Blues, modern Matchless-style speakers, and modern Celestion Alnico Gold in a 1x12 cab.
How much does the Ruby '63 cost?
The list price at launch was $399 in the United States, as reported by both Delicious Audio and Sound On Sound in 2022. In the UK it was listed at £345 each including VAT.
Can the footswitches be reassigned?
Yes. The pedal has two footswitches, and they can be reassigned using the UAFX Control app. By default the two footswitches select Live and Preset mode, versus buffered Bypass.
Sources (4)
- UAFX Amp-In-A-Box Pedals, Delicious Audio, 2022-06-16
- Universal Audio UAFX Amp Pedals, Sound On Sound (www.soundonsound.com), 2022-07
- The 20 Best Vox-Style Pedals & Vox-In-a-Box Overdrives In 2024, Delicious Audio, 2024-12-02
- Discover UAFX OX Stomp: Tone Mastery, Premier Guitar, 2024-05-18
